Process for making a reflective data storage medium
AssigneeDrexler Technology Corporation
InventorsJerome Drexler, Eric W. Bouldin
Life of this patent
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Abstract
A method for making a reflective data storage medium by creating a volume concentration gradient of silver precipitating nuclei on one surface of a silver halide emulsion coated photoplate. This volume concentration is then built up by a silver diffusion transfer negative development using primarily solution physical development until the surface becomes reflective. Lastly, a thermal annealing step is used to increase reflectivity, recording sensitivity and produce a more uniform contrast ratio.
Claims16
A method of making a reflective electrically non-conducting data storage medium comprising,
- forming an areawise, latent image exposure in a photosensitive silver-halide emulsion layer disposed on a substrate, thereby defining an area for data storage, said exposure creating an areawise layer of silver precipitating nuclei having a volume concentration gradient through the depth of the emulsion, said emulsion having unexposed photosensitive silver-halide remaining therein in concentrations inversely related to said nuclei concentration,
- contacting said unexposed photosensitive silver-halide emulsion layer with an aqueous monobath comprising a weak silver-halide developing agent for developing said latent image and a rapid-acting silver-halide solvent for reacting with unexposed and undeveloped silver halide to form soluble silver ion complexes which are transported by chemical diffusion transfer to said silver-precipitating nuclei of said latent image where silver of said silver ion complexes is precipitated and adsorbed on said nuclei in the presence of said developer acting as a reducing agent, thereby forming a reflective electrically non-conducting silver negative of said latent image in said area for data storage, and
- heating said reflective electrically non-conducting data storage medium at least to 250.degree. C. until the reflectivity of the surface increases by at least 5% of the initial reflectivity percentage.
A method of making a reflective electrically non-conducting data storage medium of the type wherein information is recorded by laser writing at a specified wavelength comprising,
- forming an areawise, latent image exposure in a photo-sensitive silver-halide emulsion layer disposed on a substrate, thereby defining an area for data storage, said exposure creating an areawise layer of silver precipitating nuclei having a volume concentration gradient through the depth of the emulsion, said emulsion having unexposed photosensitive silver-halide remaining therein in concentrations inversely related to said nuclei concentration,
- contacting said unexposed photosensitive silver-halide emulsion layer with an aqueous monobath comprising a weak silver-halide developing agent for developing said latent image and a rapid-acting silver-halide solvent for reacting with unexposed and undeveloped silver halide to form soluble silver ion complexes which are transported by chemical diffusion transfer to said silver-precipitating nuclei of said latent image where silver of said silver ion complexes is precipitated and adsorbed on said nuclei in the presence of said developer acting as a reducing agent, thereby forming a reflective electrically non-conducting silver negative of said latent image in said area for data storage, and
- heating said reflective electrically non-conducting data storage medium at least to 250.degree. C. until the absorptivity of the emulsion layer rises to at least 20% at the wavelength of a laser to be used for recording.
Dependencies are inferred from the claim text.